The study was carried out to investigate the effect of Kwandongwhasan extract and its constituent herbs onthe contractile force of isolated guineapig trachealis muscle and to elucidate its mechanism. The results of this study were as follows; 1. Kwandongwhasan significantly inhibited the contractile response of isolated guinea pig trachealis muscle by histamine. 2. Kwandongwhasan significantly inhibited the contractile response of isolated guinea pig trachealis muscle by acetylcholine. 3. Kwandongwhasan significantly inhibited the contractile response of isolated guinea pig trachealis muscle by 5-hydrooxytryptamine. 4. Kwandongwhasan significantly inhibited the contractile response of isolated guinea pig trachealis muscle by prostaglandin $F2;{alpha}$ 5. Herba Ephedrae (麻黃), Semen Armeniacae(杏仁), Cortex Mormi(紫白皮), and Flos Farfarae (款冬花), extract significantly inhibited the contractile response of isolated guinea pig trachealis muscle by histamine, acetylcholine, 5-hydroxytryptamine and prostaglandin $F2;{alpha}$. 6. Radix Glycyrrhdzae(甘草) extract significantly inhibited the contractile response of isolated guinea pig trachealis muscle by prostaglandia $F2;{alpha}$. 7. Rhizoma Anemarrhenae(知母) extract significantly inhibited the contractile response of isolated guinea pig trachealis muscle by histamine. 8. Bulbus Fritillariae(貝母) and Tuber Pinelliae(半夏) extract did not inhibit the significantly inhibited the contractile response of isolated guinea pig trachealis muscle.